10/21/2008 Case 1: Osmotic myelinosis (or demyelination) syndrome

Presented by: Dr. Ehud Lavi - New York Presbyterian Hospital

Clinical History:

A 57-year-old woman with a history of cervical cancer in 1985, with liver metastases and seizures in 2007. Her mental function declined and she was treated for status epilepticus with some resolution of the seizures. MRI T2 flair study showed multiple cerebral white matter lesions, the largest being in the occipital lobes. This was thought to be the posterior reversible encephalopathy syndrome (PRES), known to be not just posterior and not necessarily reversible. Radiology did not think these were metastases. The patient was treated for septicemia. Her responsiveness varied from unresponsive to minimally conversant. She died on hospital day 36. Autopsy showed multiple systemic metastases and the brain had no metastases. There were multiple areas of myelin loss in the white matter in the cerebrum as well as myelin loss in the
pons. These lesions were spongiform with axonal preservation, and neuronal preservation in the pons. There was no inflammation. Edema affected both involved and uninvolved areas in the occipital lobes. There was no gross spinal cord lesion, yet there was spongiform change with myelin loss and mild gliosis in the center of each posterior column, and some axonal deficit. Lateral columns appeared normal. Overall, edema, vacuolation and myelin loss corresponded to locations of radiologic changes.

Diagnostic Notes:

Osmotic myelinolysis (or demyelination) syndrome with extrapontine myelinolysis, the new term for central pontine/extrapontine myelinolysis. The differential could include acute demyelinating encephalomyelopathy, multiple sclerosis and, at least for the cord, Bt2 deficiency. The patient's chart showed only hypernatremia or normal serum sodium levels, never hyponatremia, during hospitalization. There are now several papers describing the osmotic myelinolysis syndrome in patients with hypernatremia. This is the first case where the spinal cord is included. Dr. Lavi has also seen these findings in the brain with serere hyperglycemia. Some other cases were briefly discussed that may have fit into these findings in all major CNS areas with the possibility of different types of fluid and electrolyte problems in the patients, rather than some of the traditional explanations for presumed genesis of the lesions. The consensus was that perhaps even the spinal cord lesions could be from fluid and electrolyte or metabolic
aberrations as a general explanation.

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